On the incorporation mechanism of Fe in GaN grown by metal-organic vapour phase epitaxy

We report an investigation of the incorporation mechanism of iron (Fe) as a dopant in GaN grown by MOVPE. A series of Fe doped GaN structures were studied by secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM) and X‐ray photo‐electron spectroscopy (XPS). A model is presented which describes the SIMS concentration profiles with excellent agreement, and, it is shown that Fe incorporation into GaN occurs via a surface segregation mechanism. This model is supported by direct measurement of a highly Fe‐rich layer on the surface of Fe doped GaN by XPS. Furthermore, we find that the presence of Fe on the GaN surface promotes a transition from 2D to 3D GaN growth which is confirmed by AFM measurements of RMS roughness with increasing Fe flux. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)